Reactive routing for advanced software modems

Abstract

An approach for detecting unplanned changes in the link performance of a delay tolerant network and making automatic and immediate adjustments to the contact plans of the network to provide route revisions that will reallocate traffic load to improve network performance. Physical layer information is used to predict link performance and to adapt route computation to avoid disruption and to optimize contact performance. Prediction is based on advanced software defined radio observable phenomena such as signal to noise ratio, background noise measurements, and forward error correction bit error counts. This approach can enable a delay-tolerant network node to recompute routes and revise bundle forwarding decisions automatically in response to changes in the properties of the communication link.

What is claimed is: 
     
         1 . A system for improving routing of software defined radio networks, comprising:
 a delay tolerant network having a sender including a first software radio and a receiver including a second software radio that can communicate wirelessly with the first software radio according to a contact plan;   a first transmission block module interconnected to the first software radio and programmed to encapsulate a transmit frame with a set of link performance data for wireless transmission by the first software radio;   a second transmission block module interconnected to the second software radio and programmed to receive the transmit frame that is encapsulated with the set of link performance data from the first software radio when wirelessly received by the second software radio; and   an adapter module programmed to pass the transmit frame that is encapsulated with the set of link performance data from the second transmission block module to a reactive routing module, wherein the reactive routing module is programmed to adjust the contact plan based on the set of link performance data.   
     
     
         2 . The system of  claim 1 , wherein the reactive routing module is programmed to adjust the contact plan so that the first software radio will communicate wirelessly with a third software radio instead of the second software radio. 
     
     
         3 . The system of  claim 2 , wherein the set of link performance data comprises at least one performance factor selected from the group consisting of a signal to noise ratio, a background noise level, a corrected bit error count, an uncorrected bit error count, a Doppler velocity, and a transmission power level, and a carrier drop count. 
     
     
         4 . The system of  claim 3 , wherein the reactive routing module is programmed to determine whether an aggregate bit error rate or an aggregate frame loss rate exceeds a predetermined threshold before adjusting the contact plan. 
     
     
         5 . The system of  claim 4 , wherein the reactive routing module is programmed to consider a history of link performance between the first software radio and the second software radio when determining whether to adjust the contact plan. 
     
     
         6 . The system of  claim 5 , wherein the delay tolerant network comprises an interplanetary overlay network. 
     
     
         7 . A method of improving routing of software defined radio networks, comprising the steps of:
 sending a communication from a first software radio having a first transmission block module interconnected to the first software radio, wherein the first transmission block module encapsulates a transmit frame with a set of link performance data into the communication;   wirelessly receiving the communication over a delay tolerant network according to a contact plan with a second software receiver having a second transmission block module interconnected to a second software radio that receives the transmit frame encapsulated with the set of link performance data from the first software radio;   passing the transmit frame encapsulated with the set of link performance data from the second transmission block module to a reactive routing module; and   adjusting the contact plan with the reactive routing module based on the set of link performance data.   
     
     
         8 . The method of  claim 7 , wherein the step of adjusting the contact plan comprises causing the first software radio to communicate wirelessly with a third software radio instead of the second software radio. 
     
     
         9 . The method of  claim 8 , wherein the set of link performance data comprises at least one performance factor selected from the group consisting of a signal to noise ratio, a background noise level, a corrected bit error count, an uncorrected bit error count, a Doppler velocity, and a transmission power level, and a carrier drop count. 
     
     
         10 . The method of  claim 9 , wherein the reactive routing module determines whether an aggregate bit error rate or an aggregate frame loss rate exceeds a predetermined threshold before adjusting the contact plan. 
     
     
         11 . The method of  claim 10 , further comprising considering a history of link performance between the first software radio and the second software radio when adjusting the contact plan. 
     
     
         12 . The method of  claim 11 , wherein the delay tolerant network comprises an interplanetary overlay network.